As is well known, acoustic sensors and processors are used in many military applications to locate the position of artillery weaponry for subsequent, planned retaliation and destruction. Through a programmed pattern of transducer emplacements, the locations of weapon firings can also be determined. By analyzing the acoustic signals detected by these sensors, it also becomes possible to track the movement of vehicles and of personnel, and the operations of helicopters, as well. Other military applications -- such as monitoring the activities of submarines and/or underwater personnel -- and civilian applications -- such as detecting possible areas of volcanic and earthquake disturbances -- will readily come to mind.
However, as is also well know, a substantial amount of man-machine interaction is presently involved in determining that an information signal of this type is present, and in locating the physical position of the actuating source. Thus, in one known sound ranging apparatus, acoustic signals are first recorded on a paper tape, and then analyzed by an operator to distinguish noise from signal informations, and to distinguish a single signal return from a mix of returns, as in areas of many weapon firings. As used in military applications, the operator of this apparatus then determined the times of signal return, as measured from a reference, and then makes a series of computations to determine the azimuth to a suspected target. Factors such as wind velocity and temperature are compensated, for, and the resulting corrected raw data utilized in determining azimuth intersections on a map to locate a target position.
Not only will it be seen that this process permits a degree of human error, in advertently overlooking target returns that may be present and in finding suspected targets which, in reality, are not present, but it will be seen that this process, in actual operation, could take from 5-10 minutes to provide the results desired. While such delay may not be too important in civilian applications -- e.g., in locating the positions of expectant, future volcanic eruptions --, such delay is significantly more important in military applications where "hit-and-run" tactics are oftentimes employed.